This invention pertains to telephones and, more particularly, to portable telephones for use in showers.
Cordless telephones utilize radio transmission between a portable cordless handset and a base unit which is connected (hard wired) to a telephone line to provide direct-dial telephone service to phones to others in homes, offices, vehicles and other locations. Conventional base units provide a stand and cradle to store and charge the handset when the handset is not in use. Some base units hold the handset in a vertical position. Other base units hold the handset face down in a horizontal position. The purpose of the base unit is to transmit the telephone calls over the telephone line and to cradle and charge the handset when the handset is not being used. Some base units have a light to indicate when it is charging the batteries in the handset.
A conventional cordless handset has alpha numeric push-buttons for dialing a telephone number in a manner similar to a stationary telephone. The handset may also have a flash button or base-to-handset paging button to indicate an incoming telephone call. The incoming telephone call is received and heard by the user when the flash, paging or receive button on the handset is depressed. Some handsets are automatically connected to the base without depressing a flash, paging or receive button. Typically, there are no alpha numeric push-buttons on the base unit since dialing is done from the handset.
Both the cordless handset and its base unit have an antenna. Since there are no telephone lines which connect the cordless handset to its base unit, both speech and signaling are transmitted by radio waves between the antenna of the handset and the antenna of the base unit. The cordless telephone transmits at a low power. The base unit transmits at a higher power.
Radio transmission can be accomplished between the cordless telephone and the base unit through the use of special tones rather than applying a voltage level or detecting a current as is done in overhead telephone lines. The tones will ring the cordless telephone to indicate an incoming call or will indicate a busy signal. The user of a cordless handset hears a normal dial tone when beginning to make an outgoing call and can continue dialing, i.e. pressing the alpha/numeric buttons, in the same manner as a stationary telephone with overhead telephone lines.
The cordless telephone handset can tune to frequency modulated (FM) channels assigned to the cordless telephones, such as in the 800-900 MHz range. Some cordless telephones can operate from 25-150 feet away from their base units. Other cordless telephones can operate as much as 300-600 feet away from their base unit.
Cordless telephone handsets can operate on a single channel or multiple channels, e.g. 7-100 channels. Each cordless telephone handset can have a small integrated circuit or chip providing a numeric assignment module (NAM). The NAM chip is programmed usually by the telephone dealer or installer to contain the information that uniquely identifies the cordless telephone with its base unit. The information programmed in the NAM chip includes the telephone number and serial number of the cordless telephone.
An antenna is a length of wire that radiates or captures radio signals. Without an antenna, the cordless handset would be virtually useless since the telephone would have no means to transmit and receive signals to and from its base unit. Because of the microwave frequencies utilized in cellular telephones, it is possible to make the cordless telephone antennas quite small. Cordless telephone antennas come in many shapes and sizes. Generally the antenna radiates an omnidirectional signal, i.e. one that radiates outwardly in all directions from the antenna.
Conventional cordless telephones must be used in dry places inside a house, office, etc. They can also be used outside on a sunny or dry day, provided they are within close range of its base unit. Rain, moisture or water will short out cordless telephones and may present an electrical hazard and serious danger to the user that may cause electrical shock or even electrocution to the user. Manufacturers, suppliers and distributors of cordless telephone usually warn their customers in an accompanying instruction booklet not to submerge the cordless telephone or use the cordless telephone in showers, bathtubs, rain, or excess moisture or humidity.
Many people receive telephone calls when taking showers or in a bathtub. This is very inconvenient, since the person in the shower or bath to receive the telephone call has to get out of the shower or bath, put a towel or robe over their dripping wet body and run to the telephone. Sometimes they get to the telephone after it stops ringing which is too late to receive the call. Other times the person in the shower or bath do not hear the telephone call. This can be very frustrating.
It is, therefore, desirable to develop an improved cordless telephone system for use in showers, which overcomes most, if not all, of the preceding problems.